In below link there is a underwriter's label firm , that is they produce quality assurance or guarantee labels. I think you asked this before I answered as assurer ,due to lack of context it was not correct. But I think that is just a quality guarantee tag
perhaps a native french may know exact wording

There should be an accent egu over the E. My computer doesn't do that.
An underwriter is an assistant writer, because he or she writes with a main writer. It's the same concept as a co-writer. Good luck!

Un assureur qui assure l'assureur. Toutefois je ne sais pas si c'est le contexte correct ici.